The present invention relates to medical pumps for the delivery of medicines to patients with controlled rates and dosages and, in particular, to a flow sensor for characterizing the flow of medicines from such pumps.
Medical pumps, such as syringe pumps or peristaltic infusion pumps, are known for computer-controlled delivery of medication or contrast agents (henceforth drugs) to patients over a period of time. Typically, the drug is provided in a syringe (for a syringe pump) or a flexible bag (for peristaltic infusion pump) that may be connected to an IV line attached to a needle for insertion into the patient.
When a nurse or other health care professional ministering to the patient receives the drug, the healthcare professional reviews the drug description for correctness and enters the desired dose and rate into the pump. The syringe or IV line must then be mechanically connected to the pump mechanism and the mechanism activated to begin pumping.
During the pumping operation, the flow drug may be automatically monitored by one or more sensors that detect proper operation of the medical pump. Such sensors may for example, measure line pressure, the presence of bubbles in the drug, and the like.
Knowledge of the actual flow rate of the drug in the IV line is helpful in confirming proper dose and delivery rate. To some extent, the flow rate may be deduced from the operation of the pump mechanism which provides a mechanical metering; however, even in this case, independently measured flow rate upstream or downstream of the pump may be useful to determine blockages and proper pump operation.
Measuring the flow rate of the drug is complicated by the need to preserve a sterile and typically disposable conduit for the drug and by the extremely low flow rates incident to such drug delivery.